1. Field of Invention
The present invention relates to a method of determining communication link quality employing beacon signals and, more particularly, a method of processing beacon signals from one or more communications stations to determine link quality between a communications device and the communications stations with the beacon signals including a continuous wave (CW) tone and a coded signal that are different for each of the communications stations.
2. Description of the Related Art
Satellite beacons are widely used at microwave frequencies for three applications. The first application is to use the satellite beacon in aligning the antenna with the satellite, i.e., an antenna-tracking beacon. The second application concerns operation at higher frequencies, e.g., Ku-band, where orthogonal linear polarization is used. In this application, typically two beacon frequencies provide signals that are orthogonally polarized and thus, afford a means of polarization alignment for the user to avoid cochannel interference that degrades system communications. The third application presents a stable signal for propagation research. In this application, signal level variations received by a monitoring station can be identified with propagation losses associated with rainfall, cloud cover, and other meteorological events that degrade high frequency signals.
The ultrahigh frequency (UHF) range of the radio spectrum is the band extending from 300 MHz to 3 GHz. The wavelengths corresponding to these limit frequencies are 1 meter and 10 centimeters. The UHF frequencies have link impairments that are not present at higher microwave frequencies, and by contrast, weather conditions that degrade communications at these higher frequencies do not degrade UHF frequencies. However, while higher frequency systems are degraded by principally a single factor, UHF systems are degraded by a variety of independent factors, or link impairments, that degrade communication performance.
It would be useful to be able to assist a user of a communications device, particularly a device that exploits UHF frequencies, in determining the type of service that can be achieved at a given location and time. It would also be useful to be able to provide a real time means for individually determining the factors that impair link performance and thus, allow the user to determine the type and quality of communications service that is available and assess changes in user locations that may enhance communication opportunities.